11. A 20 kW, 440-V, short-shunt, compound d.c. generator has a full-load efficiency of 87%. If the resistance of the armature and interpoles is 0.4 N and that of the series and shunt fields 0.25 2 and...

Extracted text: 11. A 20 kW, 440-V, short-shunt, compound d.c. generator has a full-load efficiency of 87%. If the resistance of the armature and interpoles is 0.4 N and that of the series and shunt fields 0.25 2 and 240 Q respectively, calculate the combined bearing friction, windage and core-loss of the machine. [725 W] 12. A long-shunt, compound generator delivers a load current of 50 A at 500 V and the resistances of armature, series field and shunt field are 0.05 ohm and 250 ohm respectively. Calculate the generated electro- motive force and the armature current. Allow 1.0 V per brush for contact drop. [506.2 V ; 52 A] (Elect. Engg. Banaras Hindu Univ. 1977)